Increasing torque with out forced induction

[uspspro]

lightweight battery/exhaust/wheels like you mentioned are good

I wonder is the driveshaft is heavy and worth changing to CF or Al?

We should start a weight loss thread.

[3MI Racing]

^^^I agree, once people start getting into yanking parts and chasing weight; it would be a nice thread to sticky.

Originally Posted by Dimman

IIf you end up making custom pistons, will they be more $ than typical because of machining the little bowl/dish for the DI?

Pricing should be about what my pistons currently are. They'll be starting from a custom forging to reduce machining anyway.

P.S. I never would have started with a piston for another engine. I don't cut corners.

[brillo]

I feel like a broken record here but given this cars weight, it just begs for a simple low boost supercharger kit. You could even skip the intercooler if the boost was low enough (5-6 psi) as I think Toyota has done this on some of their other TRD cars. All this car needs is another 40-50 hp/tq given its weight to be a rocket. a low boost supercharger kit could be a cheap and light weight way to give the car the low end kick it needs. I know some people want 300 whp but this car can get by on a lot less and be a terror.

The car can easily handle 40-50whp, all you might need are some new injectors at most. Seems like a no brainer solution for folks looking for just a bit more power down low that would be very streetable.

[Dimman]

Originally Posted by brillo

I feel like a broken record here but given this cars weight, it just begs for a simple low boost supercharger kit. You could even skip the intercooler if the boost was low enough (5-6 psi) as I think Toyota has done this on some of their other TRD cars. All this car needs is another 40-50 hp/tq given its weight to be a rocket. a low boost supercharger kit could be a cheap and light weight way to give the car the low end kick it needs. I know some people want 300 whp but this car can get by on a lot less and be a terror.

The car can easily handle 40-50whp, all you might need are some new injectors at most. Seems like a no brainer solution for folks looking for just a bit more power down low that would be very streetable.

Which is why we have several threads on superchargers.

This isn't one of those threads...

[mrtodd]

Originally Posted by uspspro

lightweight battery/exhaust/wheels like you mentioned are good

I wonder is the driveshaft is heavy and worth changing to CF or Al?

We should start a weight loss thread.

This.

[serialk11r]

Originally Posted by mrtodd

This.

There's also several weight loss threads already.

[Gardus@Supersprint]

If you use the car mostly for track days, mountain/country road or in the city centre, a easy solution to the missing torque is a reduced final ratio.

[Calum]

On one hand if you replace the rear end gears with quicker ration gear, I'm sure a taller sixth can't be that hard to install, with all the variations of this transmission that are supposed to be out there. On the other hand, I don't know how much it would be needed, if they needed to fit a sound tube to put some engine noise in the cabin. Time and research will tell, but I can forsee the above being somewhat common eventually.

[Daemione]

Originally Posted by Calum

On one hand if you replace the rear end gears with quicker ration gear, I'm sure a taller sixth can't be that hard to install, with all the variations of this transmission that are supposed to be out there.

Yikes - rebuilding a transmission with a new gear is vastly more complex than swapping the final drive gear in the diff.

In my experience, a few hundred rpm difference makes a lot less difference in your highway mpg than people would lead you to believe. Random data point: my old 5th gen Prelude got it's best fuel efficiency at close to 80mph (spinning at 4k rpms). Every drivetrain/vehicle combo is going to be different of course, so it remains to be seen how efficient these latest boxer engines will be at higher rpms.

[serialk11r]

Originally Posted by Daemione

Yikes - rebuilding a transmission with a new gear is vastly more complex than swapping the final drive gear in the diff.

In my experience, a few hundred rpm difference makes a lot less difference in your highway mpg than people would lead you to believe. Random data point: my old 5th gen Prelude got it's best fuel efficiency at close to 80mph (spinning at 4k rpms). Every drivetrain/vehicle combo is going to be different of course, so it remains to be seen how efficient these latest boxer engines will be at higher rpms.

When we're talking fuel efficiency, it comes down to how efficiently the engine can operate at extremely low loads, and that has yet to be seen. Pekingduck has said that he got 39mpg at 70 and 29.5mpg going 85-90 (yikes). With a 30% increase in the 6th gear ratio, at those load levels (we're talking about 2-3 bar MEP) it's typical to see about 10% improvement.

However, slow the car down, load requirement drops, and the difference grows bigger. Longer gears pay off more if you drive slower. Some people believe in the "de facto speed limit" of the posted speed limit + 10mph or something, so this doesn't really matter to them. Of course this depends on the engine (I imagine cooled EGR does great things for very low load operation), but you get the point.

EDIT: okay as a concrete example, I'll be looking at the 1NZ-FXE again (as far as efficiency improving features go, it's probably comparable to this engine). Notice that if you pick an arbitrary rpm, and go to the 230g/kwh mark, you'll notice that ~1/3 load reduction brings you to somewhere between 250 and 260, which is a 10% increase in specific fuel consumption. Going down to the 290 mark is another ~1/3 load reduction, so far it's following a logarithmic sort of pattern. However from here, depending on where you're looking at, reducing load ~1/4 is increasing specific fuel consumption 10%, and then it only takes a ~1/6 reduction in load to go from ~320 to ~350.

[Calum]

Originally Posted by Daemione

Yikes - rebuilding a transmission with a new gear is vastly more complex than swapping the final drive gear in the diff.

Yes, but if you do both, you can keep a similar cruising rpm. That way the noise level and your mileage wont be effected by the rear end change.

[Daemione]

Originally Posted by Calum

Yes, but if you do both, you can keep a similar cruising rpm. That way the noise level and your mileage wont be effected by the rear end change.

Of course you can do both. But I have to question to the efficacy of it . . . and any sane person will look very hard at the value, considering the cost of that kind of modification.

I'm sure a taller sixth can't be that hard to install

This is what jumped out at me. Again . . . yikes.

[Daemione]

Originally Posted by serialk11r

When we're talking fuel efficiency, it comes down to how efficiently the engine can operate at extremely low loads, and that has yet to be seen. Pekingduck has said that he got 39mpg at 70 and 29.5mpg going 85-90 (yikes). With a 30% increase in the 6th gear ratio, at those load levels (we're talking about 2-3 bar MEP) it's typical to see about 10% improvement.

However, slow the car down, load requirement drops, and the difference grows bigger. Longer gears pay off more if you drive slower. Some people believe in the "de facto speed limit" of the posted speed limit + 10mph or something, so this doesn't really matter to them. Of course this depends on the engine (I imagine cooled EGR does great things for very low load operation), but you get the point.

EDIT: okay as a concrete example, I'll be looking at the 1NZ-FXE again (as far as efficiency improving features go, it's probably comparable to this engine). Notice that if you pick an arbitrary rpm, and go to the 230g/kwh mark, you'll notice that ~1/3 load reduction brings you to somewhere between 250 and 260, which is a 10% increase in specific fuel consumption. Going down to the 290 mark is another ~1/3 load reduction, so far it's following a logarithmic sort of pattern. However from here, depending on where you're looking at, reducing load ~1/4 is increasing specific fuel consumption 10%, and then it only takes a ~1/6 reduction in load to go from ~320 to ~350.

Count me in the group of people who don't see slowing down to under the average traffic speed as an option.

The problem I see here is that we're ignoring real life variables. Traffic, incline/declines, wind, weather, the list goes on. All of those things combine to make load and changes in throttle a VERY dynamic thing, even on a supposedly flat highway. To keep a constant speed with a relatively small 2 liter engine, those variables combine very quickly to create a LOT of load on the engine, necessitating dramatic throttle changes, changing to a lower gear, or both. You're talking about an extremely low load scenario - but that isn't going to happen in real life save for rare ideal circumstances.

Out of the (VERY) few people I've ever heard of who bothered switching out their top gear for a longer ratio cog, none of them ever reported back with results worth the expense. Quite a few more people I know of have upgraded to more aggressive final drive ratios . . . (myself included) with a lot less impact on mpg than people would have you think. And if we're talking about the amount of load on the engine - we're increasing the torque to the wheels with that kind of gearing change. More mechanical advantage, and the engine doesn't have to work as hard to keep pace.

Noise/comfort is another issue. In my opinion, if it bothers you, a little bit of sound deadening (or blocking the sound tube) is a much smarter solution.

[serialk11r]

Cruising on the highway is definitely a very low load scenario. As I pointed out, constant speed cruise at 75mph is <30% of the engine's available torque. Nothing short of a 10% grade will require you to actually floor the gas all the way (10% grade interstate roads don't exist in the USA says google), for an NA car with this power to weight ratio and gearing. The dynamic load requirements make a longer gear even more important, because at the same speeds you'll inevitably be easing off the gas more, and loading the engine less, and thus using more fuel.

At any rate, for people with long commutes a small change in fuel economy adds up to a lot. Obviously, the power you have on tap decreases much faster than your fuel economy will increase, and if you're trying to special order a gearset, the time it'll take to pay back will be extremely long, but everything is a tradeoff.

By the way, the people who you've heard of switching out their top gear, are their experiences posted on the internet? I'm curious because I've only ever seen (on the internet) 1 person do it.